2-D lamp with integrated thermal management and near-ideal light pattern

ABSTRACT

A lamp is provided. The lamp includes at least one light emitting diode (LED) and an electronic circuit configured to provide power to the at least one LED. The lamp includes at least one flat circuit board having mounted thereto the at least one LED and the electronic circuit. The at least one flat circuit board acts as a heatsink to dissipate heat from the at least one LED and acts as a plurality of circuit paths for the electronic circuit and the at least one LED.

BACKGROUND

The availability of the white LED (light emitting diode) die in highpower versions, e.g., 1 watt (W) or more electrical power, has enabledthe production of lamps with several hundred to several thousand lumens(lm) of light output. The 60 W incandescent bulb produces approximately800 lumens of output, so a 110 lumen per watt plurality of white 1 wattLEDs would need 850/110 or 8 LEDs, with 8 watts of power (1 watt perLED) producing 880 lumens of light output at the emitter (LED). Due tolightpath losses, typically 90% of that light is useful, resulting inapproximately 800 lumens of net light output in the instant example.

Since the LED is a planar light source in the near field, it cannotproduce an omnidirectional cylindrical light output in the near fieldlike a suspended filament can, typically producing a Lambertian beampattern with a half power inscribed beam angle of 120 degrees, possiblyassisted by an integrated silicone dome, though the beam angle can bevaried by the LED component manufacturer by design.

So, to emulate a piece of suspended wire, heated by an electricalcurrent, the first consideration of sufficient light output is addressedby using 8 LEDs in the instant example. Those eight LEDs, in thisexample, each only produce a fractional portion of the cylinder orsphere of light produced by the filament, so they could be arranged toproduce a similar light pattern to the incandescent. Then, being a twoport device, a diode, each LED must have two electrical connections madeto it. Each LED has a forward voltage of about 3V (volts) per LED, soplacing them in series means about 24V DC (direct current) of forwardvoltage on the “array”. In one embodiment, the line voltage is nominally120V AC (alternating current) RMS (root mean square)+/−10%, so it can beas high as 132V RMS, or 187V peak. So a plurality of DC LEDs needs somemeans of changing AC to DC, as well as lowering the voltage to thenominal 24 VDC or so. The sensitivity of light output to voltage on LEDsis very high, so they are typically controlled by the lower sensitivitycurrent through them, resulting, in the instant example, in 24 VDC or soacross the 8 LEDs.

A power conversion apparatus is typically used to convert the 120 VACRMS line voltage into current through the LEDs. The mathematical productof forward voltage and current for an LED is the power applied to thedevice. Of that power, about 80% is produced as heat and 20% as light. Apower conversion block may be about 80% efficient, so thermal power thatmust be removed, and dumped into the ambient air by means of natural orforced convection, after conducting the heat away from the high densityheat flux at the devices is going to be about 8.4 watts. If we factor inthe power conversion block, and because of the power converter losses,10 W of line power must be delivered to the power converter in order forit to deliver 8 W of electrical power to the LEDs in the instantexample. The device, known as a ‘heatsink”, for moving (“sinking”) theheat away from each individual LED by thermal conduction and providingthe surface area for convection cooling is, in LED lamps’ prior art,typically comprised of relatively thick, diecast, aluminum and istypically designed to maximize material cross-section to enhance thethermal conduction process and in many instances is finned to increasethe surface area of the device to enhance convective/radiative heattransfer from the heatsink to ambient air (the “sink”). An aluminumcircuit board core (“MPCB”) may be attached to the heatsink, where theMPCB forms an electrically interconnected sub-assembly. Someimplementations actually use an air-mover (fan, as an example) toenhance the convection portion of the heat transfer process. The entireconfiguration, with all these considerations, is designed to more orless fit into the ANSI A19 specification light bulb envelope using NorthAmerica as an example, in the case of the 60 W standard service lightbulb. Known prior art implements three dimensional, rotations of aprofile in cylindrical coordinates, and few, if any are known to be thepoint sources of light that distribute light evenly in all directions toresult in the same light flux on a spherical surface a constant distancefrom that point (or, short, line) source location specified by ANSI'sA19 specification. A line source may also be used instead of a pointsource where there is a linear arrangement of a plurality ofinterconnected LEDs, which will result in a cylindrical distribution oflight in the near field. To further complicate matters, this standardservice A19 lamp is used horizontally, usually in pairs, in ceilingfixtures where half the emitted light goes upwards to the ceiling and anear-perfect reflector is rarely used to reflect the light out of thefixture down into the room. These fixtures are usually fully enclosed,so in the case of the incandescent, 120 W of heat source is fullyenclosed within the fixture, with a very poor thermal conductivity glasscover providing optical transmission and a degree of dustproofing. Someimplementations of LED lamps are as shown in the following figures.

FIG. 1 is a view of a Mirabella™ compact fluorescent lamp (CFL). FIG. 2is a view of a Cree™ LED A19 beside an incandescent A19. FIG. 3 is aview of the interior of the Cree™ bulb showing the LED arrangement on analuminum carrier attached to a heatsink, and the use of a connector“clip” which then attaches via a connector to the driver circuit board.FIG. 4 is a further view of the interior of the Cree™ bulb. FIG. 5 is aview of an EcoSmart™ bulb showing an alumina LED board mounted in analuminum heatsink, with external wiring going down inside to the driverboard housed inside the heatsink/base. FIG. 6 is a view of a Best Buy™60 W bulb, which has three aluminum heatsinks to which aluminumsubstrates are screwed, then these are wired into the base where thedriver circuit boards are. A translucent plastic shell is used betweenthe aluminum heatsink “petals”, and such shells are typically attachedwith an adhesive. FIG. 7 is a further view of the Best Buy™ 60 W bulb,showing its interior. FIG. 8 is a view of an LG™ “snocone”, which uses asimilar design as the EcoSmart™ bulb. FIG. 9 is a view of an LED bulbfrom TESS Corp., which has multiple intense LED sources, two of theseoutput 429 lumens at 8.6 W. FIG. 10 is a view of a Maxxima™ LED bulb.FIG. 11 is a view of a Phillips™ LED bulb, from blog.makezine.com. Thealuminum core LED carrier board has a connector, which screws to thelarge heatsink. Also shown are a white plastic reflector and a remotephosphor (yellow) plastic cover. FIG. 12 shows the circuit board of FIG.10, with a driver, which slides inside the aluminum heatsink and connectvia soldered wire to the screw caps and connectors to the LED sectors.

Significant costs are incurred in conventional LED lamp designs, as canbe seen in the examples, by the use of large die-cast aluminum heatsinks (16%), labor and assembly, connectors, clips, screw base, and handsoldering of the screw base and wires between the driver board and theLED aluminum core circuit board (18%). Lifetime claims of tens ofthousands of hours are contraindicated by the extensive use ofconnectors and hand soldered joints that can and will fail especiallyduring such conditions as temperature cycling or extended hightemperature operation and of voiding within thermal compounds betweenaluminum core boards and the main aluminum heat sink. See for example,FIG. 13, which is a cutaway view of a 3M™ LED bulb.

The nature of design practice among those versed in the art is, as shownin the above examples, to use a screw base, a cast aluminum heat sink, adriver circuit board or boards made of material such as FR1, CEM-3, orFR-4, connectors or solder joints to an aluminum-core circuit board subassembly, which is then mechanically attached using thermal compoundsand fasteners to the aluminum heat sink. A plastic shell is used forsuch purposes as to diffuse light, convert blue light to white light, toprotect components within the shell, to preclude a shock hazard, or in3M's case guide light, with the light originating from the individualLED sources in a singular or plurality of arranged LEDs, with everydesign shown above exhibiting a compromise to ideally having anomnidirectional point light source, or short vertical line source, asrequired in both the ANSI A19 specifications and as inherent inincandescent light bulb designs. All LED lighting (as shown above) thatattempts to replace A19 light bulbs adheres to a geometric rotation ofone or more silhouettes in a cylindrical coordinate system about avertical centerline and all attempt to arrange the LEDs in a compromisebetween such things as optical, thermal, reliability, manufacturing,safety, and electrical considerations. All attempt to couple as much ofthe LEDs' heat to the large diecast heat sink for exchanging the heat toambient air via convection, conduction, and radiation. Electricalconnections shown above are always made using a metal “Edison screw” capin the instance of a North American A19 bulb, though other means such asa bayonet or other means of termination are not precluded.

Some of the resulting light patterns from various A19 replacementdesigns are shown here. FIG. 14 is a light pattern for an A19replacement LED bulb by Cree™. FIG. 15 is a light pattern for an A19replacement LED “Lighting Science” bulb by EcoSmart™. FIG. 16 is a lightpattern for an A19 replacement LED Maxxima “snocone” style bulb. FIG. 17is a light pattern for an A19 replacement compact fluorescent lamp byMirabella.

Therefore, there is a need in the art for a solution which overcomes thedrawbacks described above.

SUMMARY

In some embodiments, a lamp is provided. The lamp includes at least onelight emitting diode (LED) and an electronic circuit configured toprovide power to the at least one LED. The lamp includes at least oneflat circuit board having mounted thereto at least one LED and theelectronic circuit. The at least one flat circuit board, or anarrangement of flat circuit boards, eliminates a heatsink casting orassembly and acts as a heatsink to conduct and dissipate heat away fromat least one LED and acts as a plurality of circuit paths for theelectronic circuit and the at least one LED.

Other aspects and advantages of the embodiments will become apparentfrom the following detailed description taken in conjunction with theaccompanying drawings which illustrate, by way of example, theprinciples of the described embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The described embodiments and the advantages thereof may best beunderstood by reference to the following description taken inconjunction with the accompanying drawings. These drawings in no waylimit any changes in form and detail that may be made to the describedembodiments by one skilled in the art without departing from the spiritand scope of the described embodiments.

FIG. 1 is a view of a Mirabella™ compact fluorescent lamp (CFL).

FIG. 2 is a view of a Cree™ LED A19 beside an incandescent A19.

FIG. 3 is a view of the interior of the Cree™ bulb showing the LEDarrangement on an aluminum carrier attached to a heatsink, and the useof a connector “clip” which then attaches via a connector to the drivercircuit board.

FIG. 4 is a further view of the interior of the Cree™ bulb.

FIG. 5 is a view of an EcoSmart™ bulb showing an aluminum-core (metalcore) LED circuit board mounted in an aluminum heatsink, with externalwiring going down inside to the driver board housed inside theheatsink/base.

FIG. 6 is a view of a Best Buy™ 60 W bulb, which has a three-petalaluminum heatsink to which LED circuit boards screwed, then these arewired into the base where the driver circuit board(s) are. A translucentplastic shell is used between the aluminum heatsink “petals”, and suchshells are typically attached by means such as an adhesive.

FIG. 7 is a further view of the Best Buy™ 60 W bulb, showing aninterior.

FIG. 8 is a view of the LG™ “snocone”, which uses a similar design asthe EcoSmart™ bulb.

FIG. 9 is a view of an LED bulb from TESS Corp., which has multipleintense LED sources, two of these output 429 lumens at 8.6 W.

FIG. 10 is a view of a Maxxima™ LED bulb.

FIG. 11 is a view of a Phillips™ LED bulb, from blog.makezine.com. Thealuminum core LED carrier board has a connector, which screws to thelarge heatsink. Also shown are a white plastic reflector and a remotephosphor (yellow—this converts light to perceived white when irradiatedwith blue light emanating from the LEDs) plastic cover.

FIG. 12 shows the circuit board of FIG. 10, with a driver, which slidesinside the aluminum heatsink and connect via soldered wire to the screwcaps and connectors to the LED sectors.

FIG. 13 is a cutaway view of a 3M™ LED bulb.

FIG. 14 is a light pattern for an A19 replacement LED bulb by Cree™.

FIG. 15 is a light pattern for an A19 replacement LED “Lighting Science”bulb by EcoSmart™.

FIG. 16 is a light pattern for an A19 replacement LED Maxxima “snocone”style bulb.

FIG. 17 is a light pattern for an A19 replacement compact fluorescentlamp by Mirabella.

FIG. 18 is a perspective view of an LED lamp in accordance with anembodiment of the present disclosure.

FIG. 19 is a perspective view of an embodiment of the LED lamp with amating slot.

FIG. 20 is a perspective view of an embodiment of the LED lamp, with amating slot complementary to the mating slot of FIG. 19.

FIG. 21 is a perspective view of an embodiment of the LED lamp, made byassembling the embodiment of FIG. 19 and the embodiment of FIG. 20together. A covering shell is not shown for clarity, and may or may notbe present for the purposes of a shell previously described, orotherwise.

FIG. 22 is a perspective view of an LED lamp with a parabolic reflector.

FIG. 23 is a circuit diagram of an electronic driver circuit that uses abuck converter to provide power to a string of LEDs in an embodiment ofthe LED lamp, detects current through the LEDs, and shuts off power tothe LEDs under certain conditions.

FIG. 24 is a circuit diagram of a further, non-magnetically coupled,electronic driver circuit for an embodiment of the LED lamp.

FIG. 25 is a circuit diagram of an electronic driver controller circuitfor an embodiment of the LED lamp, which uses a buck converter, abelieved novel neutral line connection for an LED string, and aninductor as an energy storage device.

FIG. 25a is a circuit diagram of a variation of the electronic drivercontroller circuit of FIG. 25, with an added diode as a blocking device.

FIG. 26 shows the circuit of FIG. 25 with switch T1 on, illustrating amain current path, and a small current path for the controller circuit.

FIG. 27 shows the circuit of FIG. 25 with switch T1 off, exhibiting acomparative low shock hazard risk.

FIG. 28 shows the circuit of FIG. 25 with switch T1 on, illustrating amain current path and a small current path.

FIG. 29 shows the circuit of FIG. 25 with switch T1 off, illustrating aminimal shock hazard.

FIG. 30 is a block diagram illustrating concepts of operation of thebuck converter in an electronic driver circuit for an embodiment of theLED lamp.

DETAILED DESCRIPTION

In the various embodiments presented herein from FIG. 18 onward,compatibility with the Edison screw base, known as “E26” can beincorporated, although variations could use other bases, such asbayonets. Electrical connections in the case of the Edison screw baseare made with “hot” and “neutral” wiring to the AC mains, usually withno provision for a separate ground or earth connection. Electrical shockprevention is accomplished by galvanic isolation of circuits frompossible touch points and by a “primary insulation” that is intended toprovide a dielectric barrier between hazardous voltages and, generally,the human body in order to prevent more than several milliamps ofcurrent from flowing though the body, which could cause serious injuryor death.

Various objectives were to create an optimum light pattern, to providefor heat removal in all orientations, to provide reliable electricalconnections, to minimize or eliminate manual assembly and labor andutilize machine assembly as much as possible, to comply with the ANSIA19 standard for light center and sizing constraints, for lightbulbsrequired to meet such specifications, and to eliminate or minimize theuse of hazardous and/or toxic materials including lead, mercury,chromium, cadmium, and nickel. All of these are accomplished in variousembodiments presented herein, which further achieve low cost by enablingmachine assembly methods.

FIG. 18 is a perspective view of an LED lamp in accordance with anembodiment of the present disclosure. Among other details, FIG. 18 showsa substrate (2), an electronic circuit (8), a light source (1) such asone or more LEDs positioned at a light center of the LED lamp, a lens(7) attached to the light source (1), a thermally conductive andoptically reflective area (6) acting as a heatsink for the light source(1), one or more connectors (12, 13) for a communication port, andcastellations (4) for rotary insertion of a base of the LED lamp into athreaded socket. Embodiments may have various combinations of thesefeatures, which are further discussed below.

FIGS. 19-21 show further embodiments of the LED lamp, made with morethan one substrate (2). FIG. 19 is a perspective view of an embodimentof the LED lamp with a mating slot. FIG. 20 is a perspective view of anembodiment of the LED lamp, with a mating slot complementary to themating slot of FIG. 19. FIG. 21 is a perspective view of an embodimentof the LED lamp, made by assembling the embodiment of FIG. 19 and theembodiment of FIG. 20 together with the mating slots engaged. Variousembodiments of the LED lamp can have a single substrate (2) with one ormore light sources (1), as shown in FIG. 18, a single substrate (2)coupled with a further single substrate (2) and multiple light sources(1) as shown in FIGS. 19-21, or further multiples of the singlesubstrate (2) each with one, two, four, eight, or other numbers ofmultiple light sources (1). Each face of the single substrate (2) canhave one light source (1), or multiple light sources (1). Components orfeatures to stabilize or position and/or fix the substrates to eachother, as well as any outer shell are not shown. If an outer shell isutilized, it may be ventilated by any means or may consist of a highthermal conductivity or very thin material to enhance the transfer ofheat from within the shell. The shell may also provide a thermalconduction path from thermal sources within the shell, including anyair, gas, fluid, phase-change material, or liquid therein.

Various embodiments of the LED lamp from FIG. 18 onward have a lightsource (1), comprised of a singular or plurality of light sources suchas LED, incandescent, discharge, halogen, OLED, LASER, plasma,phosphorescent, fluorescent or other contemporary light sourcetechnologies, where the arrangement of the singular or plurality oflight sources is arranged to form a close approximation of a point orline source, or any other intentional light source pattern, having alight center that facilitates the design and implementation of auxiliarylight ray processing devices such as lenses, reflectors, secondary lightor radiation emitting devices and holographic imaging devices eitherwithin, or within proximity of, the light source (1). The light source(1) may radiate light in any pattern and a plurality of devices may beused to facilitate light emission in multiple directions. The lightsources may be in elemental form (such as die), singlet or multipleindividual die, with or without phosphors and lensing, and with orwithout signal conditioning, quantizing, switching, control, and activecooling, devices and circuits.

The light source (1) is then electrically and mechanically attached to amore or less planar substrate (2) which, in a first embodiment,comprises an electrically insulating substrate. In a second embodiment,the substrate (2) includes an electrically conductive substrate. In oneembodiment the substrate, partially or in entirety, is post-formed intoa non-planar shape.

In some embodiments, a property of the substrate is not a good thermalconductor, such as a glass/epoxy circuit board known commonly as G10,FR-4, FR-406, etc. In some embodiments, a property of the substrate is agood thermal conductor, such as aluminum, copper, graphite, carbonnanotube, diamond film, etc. It should be appreciated that differingportions of the substrate (2) may have differing properties. Forexample, a printed circuit board (PCB) with thickened copper may satisfymultiple properties and material such as aluminum or titanium can beprocessed to be selectively conductive or insulating.

In one embodiment, where a portion of the substrate (2) is a poorthermal conductor, a layer is created that provides a low thermalresistance, comprised of materials such as a graphite, copper, aluminum,diamond film, etc. In another embodiment of the second embodiment, alayer is created that provides a high electrical breakdown, lowelectrical conductivity, electrical insulating material such as aluminumoxide (“anodizing”), chemically or thermally applied materials such asceramics or glasses, or vacuum deposited materials such as silicon-basedcompounds and carbon-based films like diamond.

In one embodiment, electrically conductive layers are created on aninsulating layer to provide interconnect between circuit components andelements, which also can include connections to a singular or pluralityof the light sources (1). In an alternate embodiment, an electricallyand thermally conductive substrate has material removed, such as bychemical or machining means to form individualized electrical andthermal conductors. In a second alternative, individual conductors areformed additively by means such as vacuum deposition, ink or pastedeposition, and electroforming.

Many embodiments have a projection of the maximum envelope prescribed byindustry standards, as well as a familiar silhouette, and in manyembodiments that maximum envelope is specified by ANSI for the A19 formfactor “standard service light bulb”. In at least one embodiment, thesubstrate consists of a planar FR-406 insulating material and places thelight sources at an “optical center”. In some embodiments, the lightsources (1) are placed on both sides of the substrate (2) with the lightsource(s) optical centroid at the optical center. In one embodiment, thesubstrate is cut (3) in a convex arc about the optical center, such ashaving an approximately 34.29 mm radius, circumscribing approximately255 degrees. The “primary shape” being described for one embodiment, infurther embodiments, may be punctuated with slits and other features.The convex arc is then met at a vertical tangent by a concave arc, suchas having an approximately 39.538 mm concave radius, circumscribingapproximately 38 degrees. In some embodiments, this concave arc is thentangentially met by an approximately 6.35 mm radius convex arc thatcircumscribes approximately 45 degrees, the far end which meets a 45degree chamfer of approximately 6 mm in length. In some embodiments, the45 degree chamfer then meets the “vertical mating section”, which isnominally vertical and displaced horizontally from the optical/geometriccenterline by a standards-specific dimension such as approximately 13mm.

The vertical mating section in one embodiment is dimensioned such that,despite the primarily planar geometry of the substrate, it will matewith standard lamp base sockets, such as E26 (used in some embodiments)and E27 screw bases and GU-24 pin base sockets. The E26 screw base, orEdison base, is specified as 7 threads per inch, with radiused threadprofile using a 0.0469 inch radius and a maximum root diameter of 0.974inches. In one embodiment, the thread profile is cut into the edge ofthe substrate, compensating accordingly since a square substrate edgewill usually result. In another embodiment the edge is filleted toclosely approximate a rotation about the central axis. In a furtherembodiment, a separate conductive, insulating, or a combination thereof,2 dimensional or three dimensional “lamp base” is attached.

In another embodiment, “castellations” (4) (which may also be calledcrenations, or crenellations) are created by means such as drilling 3/32inch vias on thread pitch centers on both left and right sides duringthe processing of the substrate, with the opposite sides being offsetvertically by a half thread pitch. This method, in some embodiments,yields the ability to work with both left handed and right handedthreaded sockets without any changes to the substrate layout orgeometry. During the excise of the outline from a panel by milling, theoutline is milled such that the milling operation occurs approximatelyat or outside the midpoint of the thread crest and root, where thetangency occurs as well as a change in slope. This allows the threadroot to have remaining conductive material from the prior via to makeelectrical (and possibly thermal) contact with the lamp socket. Inanother embodiment, no castellation vias are used and the thread profileis milled into the edge of the board, fully implementing the threadprofile of root and thread, on totality, partiality, or spatiallyoversampled, with appropriate root diameter compensation (for the flatmilling operations), with left and right sides of the vertical matingsection being offset by a half thread pitch. These edges are then “edgeplated” or “slot plated”, which is a known operation by substratesuppliers. In another embodiment, the substrate outline is routed tocreate fitting mating features such as “bayonet” pins on the edges withthe appropriate edge plating to emulate the placement of eithercylindrical, or cylindrical bi-pins with a “T” cross-section, or slotsto facilitate insertion of conductive or insulating pins as required.

The vertical sides of the vertical mating section, left and right, makeelectrical contact with the screw base socket, which is a connectionsuch as “neutral”. Ground is not present in Edison screw bases, whichpresents problems with safety. The very bottom extent (5) of thesubstrate profile consists of an electrical connection, such as to“hot”, which in some embodiments is an edge plated area on the bottomedge. In another embodiment, a conductive device, conductor, structure,or layer is attached, mounted, applied, or connected to the conductor(s)on the substrate which then makes contact be extending beyond the bottomedge of the substrate, eliminating the edge plating step.

In order to conduct and eventually radiate or convect heat away from thelight source(s), a thermally conductive area (“TCA”) (6) is providedthat provides a low thermal resistivity path from the heat source (thelight emitting device(s)) to its largest extent. The surface area of theTCA (6) is then used to transfer heat by methods such as radiated andconductive, or as is the case in many embodiments, by convective means,possibly by radiated as well. The TCA (6) may have its thermalperformance enhanced by such means as adding layers, coatings,materials, or geometrically by adding thickness or increasing surfacearea by surface treatments such as etching channels, plating or bondingfins or pins, or increasing emissivity by anodizing, by chemicaltreatments such as patinas or blackening copper, or by bonding graphiteor inks. In many embodiments, the TCA (6) is comprised of “thick copper”and is part of the substrate processing. The substrate processing canenhance the copper thickness by methods such as the application ofthicker foils and subtractively processing them either prior or postbonding to the substrate, or by use of a seed layer of conductivematerial, such as copper, copper foil, graphite, conductive ink, orelectroless conductive materials; which are then etched as, or if,needed, then electroplated to the larger thickness. In anotherembodiment, the thicker metal is applied using deposition methods suchas vacuum deposition or flame spraying. The thicker copper may befurther processed by subtractive or additive methods to provide a meansfor attaching circuit nodes to the thicker copper or thermal material.

The light source (1) is generally a Lambertian source or possibly apoint source or limited length line, source, with light intensitiesvarying with angle in any plane orthogonal to the substrate plane.Ideally, there would be no variation and light intensity would be thesame, irrespective of angle, but light distribution clearly is not idealin many of the implementations of “three dimensional” LED lamps as shownin the previous figures, with the popular “snocone” implementationsbeing among the most uneven. In present embodiments, a corrective lens(7) may be used to correct the light pattern from the light source(s)(1) to a near-ideal pattern, such as over a full hemisphere or cylinder,while preserving the light center required by external opticalprocessing elements, such as parabolic reflectors, which assume point,or rarely line, sources. In another embodiment, a “remote phosphor” domeor lens (7), which produces a color shifted, filtered, narrowed orbroadened spectrum, and may produce light by means such asphosphorescence or fluorescence, as a result of being impinged withenergy from a source such as a blue LED, x-ray source, electricaldischarge, laser, or other such high energy photon, electromagnetic,acoustic, or particle source. In another embodiment, a lens function iscombined with the “remote phosphor” functionality in a dome or lens (7).In yet another embodiment a diffuser is used either in combination witha corrective lens, or as a light diffusion device covering the lightsources, to reduce glare and provide a more uniform light source. In oneembodiment, the element (7) serves as a protective device against suchthings as dust, dirt, contaminants, chemical attack, or mechanicaldamage. The element (7) can be a separate or integrated device with thelight source or the substrate. The element (7) can have polarization analignment features for alignment with, or of, devices and structuressuch as the substrate (2), the element (7) or the light source(s) (1).In one embodiment, the element (7) can be oriented, either as a singularunit, or as a plurality in an assembly, to perform a variable orquantized optical function such as filter, emitter, intensitydistribution, intensity level, wavelength shift, polarization,collimation, beam width, or focal point adjustment. In one embodiment,the element (7) serves as a coupler to reduce losses in attachingdevices such as a waveguide or amplifier.

With reference to FIGS. 19-21, in one embodiment, there are multiplesubstrates (15, 17) with TCAs (6). Each substrate (15, 17) provideselectrical and thermal connections for a singular or a plurality oflight sources (1). In one embodiment, the first substrate (15) has aslot (16). A second substrate (17) has a mating slot (18) such that thefirst and second substrates (15, 17) can mate by means known to thoseversed in the art, such as soldering, connectors, snap connections,mechanical means using the substrate material such as slots and tabs,conductive tabs, etc. In one embodiment, the first substrate (15) hasboth the light sources (19) and all supporting circuits on it and thesecond substrate (17) has light sources (20) on it. A means is providedto connect, electrically from the light sources on the second substrateto the first substrate. In one embodiment, features are provided in aprotective cover (21) that may provide mechanical stability and/protectelectrical connections. Rather than being limited in power dissipation,e.g., about 10 W of heat per TCA (6) in an A19 form factor, whichdelivers a net light output at today's efficacy levels of about 800lumens, or the equivalent of a 60 W incandescent light bulb, additionalsubstrates with TCAs (6) increase the total TCA (6) surface area. In oneembodiment, (24) adding one additional TCA (6) doubles the powerdissipation capability, and therefore the lumen output to about 1600lumens today which is equivalent to a 100 W incandescent light bulb. Inanother embodiment the TCA is comprised of a “standard” thicknesscircuit board foil and the second substrate is used to increase thesurface area to compensate for the lower heat spreading capability ofthe thinner foil. The substrates, being more or less planar, allowsingle or double-sided surface mount manufacturing methods, ending withthe assembly of a plurality of substrates, any protective covers, aswell as any corrective lenses, diffusers, or reflectors that may beneeded. In one embodiment, the TCA (6) metallization (22), such aspolished nickel or chromium, is used as an integrated reflector as wellas a heat spreader and ambient air thermal exchanger.

In one embodiment, slots (23) are provided in the TCA (6) to accommodatelamp shade clips, a leftover of the incandescent bulb days where aspring wire pair of loops is used to clip onto the incandescent bulbenvelope as a means to attach a lamp shade. It is left to those versedin the art to provide additional constraint structure and devices formounting said clips to stabilize the lamp shade.

FIG. 22 is a perspective view of an LED lamp with a parabolic reflector.In one embodiment, the ability to cluster light sources on the TCA (6)as near-perfect point or line sources lends itself to a PAR (ParabolicAluminized Reflector) lamp (34) configuration. In many embodiments, asingular substrate with TCAs (6) is used. In another embodiment, aplurality of substrates and TCAs (6) is used, as previously discussed.In one embodiment a reflector, constructed from materials such aselectroformed nickel, copper, plastic, or chrome or aluminum, is affixedto the TCA (6) by means well known to those versed in the art. In oneembodiment, the locating features made of solderable materials are usedto solder the reflector to the TCA (6). In another embodiment, thereflector is used as a further thermally conductive material thatprovides a larger area of exposure to the surroundings to dissipateheat. In the embodiment of a PAR lamp (34) shown in FIG. 22, anarrangement of parabolic reflectors (35) are shown, with the furtherprovisioning of an additional substrate not shown for clarity. As can beseen, the light sources (19) are clustered, providing the closestapproximation to a point light source that is possible for a given lightemission surface area. Also not shown are seals against dust andmoisture, ventilating or cooling features, or any optics, such asdiffusers or lenses related to the reflector or substrate. Thedepictions in the diagrams are schematic and illustrative and are notoptimized for form factor limitations.

With reference back to FIG. 18, in many embodiments, a circuit (8) isprovided for electronic functions such as control, monitoring,maintenance, up conversion, down conversion, filtering, safety,illuminance, communications, interface, or signal conditioning. In oneembodiment, the circuit (8) consists of active and passive elements anddevices on both sides of the substrate, including such devices asinductors, capacitors, transistors, resistors, and integrated circuits.In one embodiment, the circuit (8) monitors the current and voltageto/from hot and neutral mains connections, determines any difference orthreshold levels, and invokes protection, adjustment, and reporting suchas shutdown, clamping, crowbarring, alarming, increasing or decreasing acontrol parameter or output, and messaging. In one embodiment, thecircuit (8) delivers a predetermined maximum amplitude to the lightsource(s) such as current. In another embodiment, the circuit (8)monitors the input waveform and adjusts control parameters or output,such as switching into the circuit, or bypassing, singular or aplurality of LEDs such that their forward voltages in combination withthe voltages in other control circuits, such as a current source, equalsthe input waveform voltage or current. In one embodiment, all of theLEDs are bypassed when all of the forward voltages are excessive,leaving the current source to sink current, facilitating dimmingcontrol. In one embodiment, the switching or bypassing of singular or aplurality of LEDs is binary weighted. In one embodiment, the number ofVf levels are quantized such that when used on a certain line frequencysystem, the total number of switchings does not exceed a predeterminednumber of times per period of time. In one such embodiment, thepredetermined number of times per period of time is bounded by theminimum operating frequency requiring electromagnetic interferencecompliance being 9,000 Hz and in one embodiment the line frequency is 60Hz, the Vf is comprised of two 3V LEDs in series to make 6V, the linevoltage is 120 VAC+/−10% and 187Vpeak resulting in no more than 32levels between 0V and 187V or 64 switchings per half cycle or 128switchings in a 60 Hz cycle resulting in 7,620 level switchings persecond. In another embodiment, the frequency is fixed to 9,000 Hz, oranother such number setting a maximum desired frequency of operation,and the combination of Vf of individual, or a plurality of, LEDcombinations and a current source and other circuits if needed is set tobe less than or equal to the instant line voltage, or some otherreference representation, at the time of each of the 9,000, or othersuch number, clock transitions or levels or cycles. In anotherembodiment, the circuit (8) maintains a constant ratio of input voltageto output current or a constant phase of input voltage to output currentin order to appear as a circuit element such as a resistive or reactiveload impedance of constant or preset or determined value. IT should beappreciated that the use of “input voltage” also refers to anyrepresentation of a desired waveform throughout. In yet anotherembodiment, the circuit (8) holds a control parameter or output valueconstant. In one embodiment, the circuit (8) monitors temperature andchanges control parameters or adjusts the output to maintaintemperature, or to keep from exceeding maximum temperatures, or to causethe system or devices to not exceed minimum temperatures. In oneembodiment the circuit (8) consists of a function known to those versedin the art as a “driver”. In one embodiment, the circuit (8) monitorsthe output of the light source(s) (1) or the element (7) and adjustscontrol parameters or output to maintain a preset or setpoint level orcondition, or to set limits on operating levels. In one embodiment, aspecial code is stored upon the device, such as a serial number inmemory or a serialized microcontroller as is found in ARM processors.This code is then transmitted by modulating the intensity by a meanssuch as switching the LEDs off at predetermined points in time that areintentionally visible or invisible to the human eye. In one embodiment,this modulation occurs at a fixed point in the AC waveform, such as theexpected peak voltage point. In one embodiment, the code in its entiretyis transmitted at random points in time, though still at an expectedpoint on the AC waveform. In one embodiment, a device is provided toallow the detection and reading of light pulses, or their absence, atcertain points in the AC waveform, allowing reconstruction of thedevices serial number or device code. In one embodiment, a database iskept of such codes or serial numbers for the purposes of establishingauthorized use of the device at a particular location. In oneembodiment, a portable or fixed location device monitors or samples theLED modulation and determines conditions such as theft, maintenance orfault codes, system telemetry, building or power management, or sensorcommunications. In another embodiment the modulation can be receivedfrom other devices or systems for purposes such as control, theftdeterrence, fault coding, security, etc. In one embodiment, a line ofsight or reflector is used for purposes such as room occupancy,security, etc.

FIG. 23 is a circuit diagram of an electronic driver circuit that uses apower converter, such as a buck converter, to provide power to a stringof LEDs in an embodiment of the LED lamp, detects current through theLEDs, and shuts off power to the LEDs under certain conditions. Withouta ground connection, a conventional ground fault circuit interruptercircuit is not possible for safety. In one embodiment the current in thehot side of the circuit, near the entry point to the unit or at or in anactive device nearest thereto, is compared to the current in the neutralside of the circuit near the entry point to the unit or at or in anactive device nearest thereto. In another embodiment, the currentexiting a protected housing, destined for remote circuits or equipmentis compared to the current entering the protected housing. Safetystandards allow a maximum “leakage current”, which is assumed to bedirected through personnel or equipment. One embodiment compares thedifference between the neutral and hot side currents, or arepresentation thereof, and when that difference, due to externalleakage through such things as personnel, fauna, or equipment, exceedsthe leakage current limit, the device is reverted to a safe mode such asbeing turned off, disconnected, or “crowbarred” by shorting the line andneutral nodes to activate circuit protection shut down devices such asfuses or circuit breakers. In one embodiment a delay is introduced toprevent reactivation of the circuit within a predetermined period oftime. In another embodiment an accounting of events, or their timing,disables the device for a predetermined time, which could beindefinitely or in another or the same embodiment until the power iscycles or the system is otherwise commanded or signaled to resume normaloperation. One embodiment is shown (8). The current exiting and enteringa housing, e.g., protective cover (21) crosses the dashed line (26) intothe TCA (6) to power the light sources (1,19, 20, 27). The TCA (6) issubject to being connected to an object or person (or fauna) should aninsulation failure occur in a cover insulating dielectric, such as amolded plastic or conformal coating or film, thereupon. Since currentnormally flows in a loop, we expect current (28) to equal current (29).In one example, a scratch is present in the dielectric film as a firstfault. A human touches the scratch and provides a path for some currentto flow to earth. This now means, in one half of the AC cycle (currentflows to/from earth are opposite in the other half cycle) current (29)is less than current (28) by the amount of current flowing to earththrough the person. There are safety limits on this amount of current, acurrent threshold that may not be exceeded. One embodiment provides ameans for sensing this difference in current (28) and (29), with oneembodiment using a resistor network such as the highly sensitivebalanced Wheatstone bridge configuration comprised of the four elementsR16, (R18+R19), R17, and (R15+R14). Other means, such as hall sensors,current transformers, etc., may also be used. Resistor R16 sensescurrent (28) and R17 senses current (29). Resistor R20 is merely usedfor current control by the driver for the LEDs and may or may not bepresent in various embodiments. One embodiment measures the voltage (31)and compares it to the voltage (30)—both should be approximately equalif the currents (28) and (29) are more or less equal and the resistorelements of the bridge are more or less balanced, which they are bydesign. Resistor pairs R14/R15 and R18/R19 form voltage dividers forvoltages (31) and (30) respectively, bringing the voltages withincompliance and common mode range of the subsequent measurement circuits.Because the ratio of peak current to the leakage current through thehuman is so great, a low offset amplifier, X3A is used in one embodimentto amplify the current difference voltage analogs by a factor of 100. Inone embodiment, a microcontroller U1 utilizes an integrated analog todigital converter to convert the amplified/conditioned signal from X3Ainto a binary value that can be conditioned and filtered, if necessaryand then compared to a preset threshold. If the threshold is exceeded,one embodiment shuts down the power conversion by shutting offtransistor switches T2 and T3. In another embodiment a double pole relayis used to fully disconnect any line and neutral connections to the twowires crossing the dashed line (26). In another embodiment a crowbarcircuit is triggered which then activates circuit protection devices,such as fuses and circuit breakers either within the system or externalto it. In other embodiments, the system is comprised of an AC-powered,or other shock hazard, apparatus other than one comprised in whole or inpart of LEDs.

There is a class of lighting luminaires that mount to a ceiling andutilize one or a plurality of light bulbs in horizontal orientation.Using lamps that distribute light cylindrically or spherically, whichdescribes many known LED, CFL, halogen, and incandescent, lamps, half ofthe light is directed towards the ceiling plane, or otherwise in anundesirable direction. In most luminaires, the area above the lamps isnot a highly polished reflector. With this consideration, up to half ofthe light output may be wasted. As an example, most of these luminairesuse two 60 W incandescent lamps, with their longest axis of symmetrybeing horizontal. A typical dual LED installation would use 20 W ofelectrical power, again wasting half the light in an upward direction,even worse for a “snocone”, since it will beam light out sideways, andprovide little illumination below the luminaire, where the light isneeded. Research has shown that lamp sockets are not consistentlyoriented and merely screwing the bulb in results in an inconsistent lamporientation between socket and bulb combinations—it can typically be 0degrees or 180 degrees in the socket as far as where it stops when fullyscrewed in. The center spring contact, in the case of the Edison screwbase socket is also inconsistent in its connection range of complianceto where backing off the light bulb by amount of being screwed in cannotachieve proper bulb orientation if a bulb were created with ahemispherical light pattern.

One embodiment has an orientation sensor or device that determines bulborientation. Some embodiments have a plurality of directional lightsources. In one embodiment, there are two light sources (1) and opticalelements, e.g., lens (7), with each pair (1, 7) directing light in afull or partial hemisphere above the surface of the substrate. Thesensor or device then acts to turn off, or turn on, one of the two lightsources (1) and/or optical elements, e.g., lens (7) by electrical,mechanical, photonic, or other means, or when the longest axis ofsymmetry is vertical with the screw base up or down both sides areactivated.

In one embodiment, a singular or plurality of two terminal electricaldevices, LEDs (1), as the light sources (1), are interconnected, withone on each side of the substrate. In one embodiment incoming currentcomes up to the light source (1) on the backside of the substrate from arectifier and filter circuit (back side of the substrate and thereforenot shown). The second terminal then connects to a via (“commonterminal”) which brings an electrical connection to the top side lightsource (1)'s first terminal. The light source (1)'s second terminal isthen connected to the driver circuit (8). A pair of common surface mountjumpers (9), a conductive metal strap that joins two spatially separatedsurface mount pads electrically by “jumping over” and not being incontact with the substrate or any conductor between the two surfacemount pads, are each placed on two pads, one on each side of thesubstrate. One of the pads on each side is connected to the commonterminal. The jumper (9) on the backside has its second pad connected tothe second terminal of the front side light source(s) (1). Conversely,the jumper (9) on the front (visible) side is connected to the firstterminal of the backside light source(s) (1). The substrate has a largediameter via (10) placed under the jumpers (9), offset from theircenters in one embodiment, and connected to the common terminal. In oneembodiment the via (10) has a barrel, vee, or “u”, instead of acylindrical, cross section. Prior to placing the second conductor, aconductive element, such as a ball (shown inside (10)), is placed in thevia (10) and the jumpers (9) are soldered to their pads. The captiveball's function is to connect the via (10) walls to either the top orthe bottom jumper (9) when the bulb is horizontal. A barrel, vee, or“u”, instead of a cylindrical, cross section prevents the via (10)connection in other bulb orientations. In one embodiment, theorientation switch or sensor is a component that is connected to theaforementioned pads, in another implementation, an orientation sensor orswitch is connected to a driver circuit. In one embodiment, if the bulbis horizontal, the ball will connect the lower jumper (9) to the via(10). The via (10) is connected to the common terminal. Since the jumper(9) is connected to the LED (1) on the opposite side, the ball'sconnection will short out the top LED (1). The driver circuit (8) drivescurrent to the two LEDs or other light sources (1) that were in seriesbut on opposite sides of the substrate (2). With one LED or other lightsource (1) shorted, the second LED or other light source (1) isoblivious and continues to receive the same current from the drivercircuit (8) as it did without its mate light source (1) shorted, whichmeans it continues to put out the same amount of light. In oneembodiment, a horizontal orientation increases the driver currentslightly to account for some of the light that would have been reflecteddownwards by the luminaire for a conventional bulb design that does notincorporate present embodiments. So, a dual 60 W ceiling fixture'sincandescent bulbs can be replaced by two LED lamps with embodiments ofthe presently disclosed orientation sensor, resulting in 10 W of powerconsumption for the same light output, respectively. This savesconsiderable power consumption as compared to 120 W for the dual 60 Wconventional incandescent bulbs, or 20 W for two LED lamps of 10 W each.

In addition to the driver circuit (8), one embodiment has an intelligentdevice (11) such as a microcontroller or FPGA (field programmable gatearray) to intelligently manage, communicate, control, and senseconditions and then provide control signals to the driver circuit (8).In one embodiment, the intelligent device (11) is an ATMEL AVR™microcontroller. In another embodiment, it is an ARM™ basedmicrocontroller. In yet another embodiment, the intelligent device (11)utilizes common operating systems or development tools such as Arduino™,Linux, iOS™, Android™, or a realtime operating system and programminglanguages such as assembler, C, BASIC, FORTH, etc. In one embodiment theintelligent device (11) is preprogrammed. In another embodiment, theintelligent device (11) can be programmed “in circuit” by a means suchas a set of pads, by connection to the device pads or pins, through theuse of a connector (12, 13), or by providing a method of programming viaa communications protocol such as wireless, RS232, Infrared, serial, oruniversal serial bus (USB). In one embodiment, a USB connector isimplemented simply with a pair of cutouts and circuit board traces (14)to allow secure programming of the light bulb by a wired connection withan intelligent or computing device. Further circuit board traces (14)couple components of the electronic circuit 8 to each other and to thelight source (1). The intelligent device (11) monitors and controls thelight bulb functions, interfaces to the outside world and to sensors,accepts different programming at varying times as needed, providescommunications, facilitates functionality development, and controls thedriver circuit (8). In one embodiment, the intelligent device (11)controls the dimming function (which facilitates on/off by that veryfunction) of the light source(s) (1) using pulse width modulation (PWM).In another embodiment, the intelligent controller controls the analogdimming functions of the driver circuit (8). In one embodiment, arepresentation of the full wave rectified line voltage is presented tothe device for conversion and analysis, facilitating brownout andblackout prediction, line voltage monitoring, and power linecommunications receptions for protocols such as X10. In one embodiment,the intelligent device (11) controls a plurality of drivers and theirsubsequent LEDs. In another embodiment the line voltage and waveshape issensed and the driver is adjusted accordingly, such as a 120V AClightbulb in normal operation encountering a blackout, another means isprovided to switch in an auxiliary supply such as solar or a batteryhaving a lower or higher DC voltage. In yet another embodiment a batteryand a charger circuit is provided in the light bulb for short termillumination should power be disconnected. In a further embodiment, thelightbulb looks into its power inputs to see if a switch has beendisconnected, determined by an extremely high impedance, or whetherpower has failed, determined by a finite impedance measurement. In yetanother embodiment, a light source of differing characteristics is usedas an alternative to the main light source and is activated by meanssuch as a sensor measurement, communications link, or preprogrammedinterval. In one embodiment, the main light source is a singular orplurality of LED(s) and the alternate light source is an infraredemitting LED or plurality of LEDs enabling security camera illuminationwith the room being dark in the visible range.

A set of programming and expansion connectors (12, 13) facilitate insystem programming and provide access to every pin of the device and toan onboard regulator. An additional pair of pins provides access to fullwave rectified AC line voltage. In one embodiment, pins are alsoprovided to enable access to the TCA (6), enabling its use as acapacitance sensor for “touch switch” and gesture sensing. The expansionconnectors are in a specified geometry that allows the attachment of asingular or plurality of circuit boards to enable additional hardwarefunctionality, along with the attendant software applications (“apps”)to control the light bulb. Such hardware includes functions such as: amore powerful microcontroller, Arduino or other generic or ubiquitouscontrols or accessories, motion sensors, audio sensors, microphone,audible devices, WiFi, Bluetooth, Zigbee, ISM band, GSM band, timers,batteries, clocks, displays, additional light sources and drivers,smartphone emulators, memory, port expanders, etc. What is alsosupported, in some embodiments, is not just the ability to put expansionboards on a light bulb, but also the ability to download, install andrun apps, a developer site for light bulb apps and hardware development,and an apps store associated with a light bulb's software “apps”distribution. Apps create and increase the hardware functionality, andinclude such functions as time to on, time to off, time on, time off,dimming, clap on clap off clap dim, flashing, strobe, sound sensitive“color organ”, smartphone control and communications, machine to machinecommunications, Internet control and status, web appliance, motionsensing and motion filtering, infrared remote control learning andcontrols, etc. With these capabilities, not only does LED lighting havelong life, it also will have a long FUNCTIONAL life.

The use of the planar substrate, fabrication of multiple units on apanel or substrate, machine surface mount or bonded assembly of allcomponents or subassemblies, and no hand assembly or soldering, meansvery low cost and high quality, yield, life, and reliability.

Further embodiments of the electronic circuit 8 are described below withreference to FIGS. 24-30. These embodiments provide shock hazardmitigation in non-magnetically-isolated power supplies.

Classical paradigms and approaches to voltage safety in power supplydesign, such as those found in solid state (or “LED”) lighting are toimplement a magnetically isolated and coupled power supply, topologiesthat are well known to those versed in the art. The magnetic isolation“floats” the secondary side of the transformer, thereby providing novoltage potential with respect to earth, mitigating the possibility ofan electric shock. A transformer costs well over $1, typically $1.50 forgeneral lighting applications, whereas an inductor is about $0.30. Thetransformer requires dual windings that are separated from each other byan insulator rated for more than 1000Volts. An inductor only needs toinsulate wire to wire in the same winding, so can get away withsignificantly lower rated insulation. With two windings, and theinsulation between them, transformers are usually much larger than aninductor for the same power rating.

FIG. 24 is a circuit diagram of a further, non-magnetically coupled,electronic driver circuit for an embodiment of the LED lamp. This is anon-magnetically coupled, “safe” power supply. The LED string isreferred to the neutral (N) side (at the breaker box) plus one diode (D2or D6) V_(f) forward voltage drop. A typical string of 1 W white LEDs,with a V_(f) of 3V, in an application needing 900 lumens would need 9devices, assuming an efficacy of 100 lumens/watt (it follows, oneone-watt LED per 100 lumens). The string V_(f) would then be 9 devicestimes three volts apiece, or 27V. Low safety-voltage limits are 35Vp-p,so adding the forward drop of one silicon (or other material or devicetype performing functions such as switching, current steering, orblocking) diode of 2V means the worst case exposure in the LED string is29V. A shorted diode (D2 or D6) enhances the situation by reducing theworst case voltage with respect to Neutral to 27V. An open circuitfailure of the diode (D2 or D6) in this embodiment presents a shockhazard for a double fault condition if insulation is present on theelectrical conductors in the system and has been compromised.

A major downside of the illustrated approach here is that TWO inductors,L3 and L1 are required, as are two independent buck switching(synchronous or asynchronous) and current control circuits, which wouldappear in the locations of the circles. This doubling of componentstakes up board area, increases packaging volume needs, increases noiseemissions, and increases cost significantly. Though diodes are shown,those versed in the art can easily foresee using switches (such astransistors) in their stead.

FIG. 25 is a circuit diagram of an electronic driver circuit for anembodiment of the LED lamp, which uses a buck converter, a neutral lineconnection for an LED string, and an inductor as an energy storagedevice. Rather than duplicate components, the embodiment shown in FIG.25 switches connectivity during the start of each AC half cycle to acore, reduced component-count, grouping.

The classical bridge rectifier, with its 4 diodes, creates a “DC”supply, by swapping Neutral and Line connections every half cycle, withthe Line being a positive half sine wave voltage with respect to Neutral(earth), or, on the next AC half cycle, a negative half sine wave withrespect to Neutral. Any attempt to lower the voltage in one half cyclewith respect to a designated rectifier-output “ground” at the supplyoutput is met with futility when the next half cycle switches in thealternate rectifier diode pair, bringing the full peak voltage in theopposite polarity to the output “ground” with respect to the earthedNeutral connection. This then leads to those versed in the art resortingto magnetic isolation, which allows one leg of the output to bedesignated as ground, the other leg to be rectified to produce apositive only output with respect to that ground. This embodiment doesnot use the classical bridge rectifier, as can be seen by the way any ofthe diodes are connected to either Line or Neutral in the figure.

Upon inspection, it can be seen that there is only one buck converter(one controller, one switch, one inductor) in FIG. 25, with thisembodiment showing an asynchronous buck converter configuration. As forthe previously discussed FIG. 24, the diodes and transistors in oneembodiment may be replaced with devices such as switches or transistors.The Neutral line connection is connected to earth with a low impedanceat some, typically singular, point in the power network to which theinvention is connected. The embodiment, in FIG. 25 above, implements abuck converter, using a buck controller device, U3, a switchingcomponent device T1, an energy storage device, such as an inductor L2;and a load such as the one used in the present embodiment comprised oflight emitting diodes (e.g., LEDs, represented as diodes, in oneembodiment), or “load equivalent devices”, in a singular or plurality ofdevices such as shown in the figure as devices D11-D19.

When the Line is positive with respect to Neutral (or eventually“earth”), current flows from Line through D6 (ignoring one embodiment'sEMI filter that is placed between these nodes—a noise filter and itsplacement are not at the core of the embodiment), then splits to supplythe buck controller and other “low voltage” circuits' supply currents bybeing connected to a device, such as a limiting resistor R12 or ablocking diode. Alternatively, this connection could have gone to aregulator or the buck controller's HV pin 8 and to switch device T1. Inone embodiment, current control is desired and is sensed through R8. Aswitching device, such as diode D4, connects one embodiment's controllerground connection to one end of the energy storage device, in oneembodiment, an inductor (L2), then through a current steering device D9,to which the positive side of the load, LEDs D11-D19, is connected. Thenegative side of this load's current is then steered by either D5 whenthe switch T1 is on, or by steering device D8 when the switch is off andcurrent circulates from the energy storage device L2. The current flowpaths for this half of the AC cycle, with switch T1 on and off,respectively, are shown in the following figures. The figures illustratea main current path, a small current path for the controller circuit andfor a damper resistor in the EMI filter implementation. It should beappreciated that the filter is not an essential part of the embodiment.

FIG. 25a is a circuit diagram of a variation of the electronic drivercontroller circuit of FIG. 25, with an added diode as a blocking device.Diode D11 is added as a block for the driver during bench testing. Invariations, diode D11 can replace R12 in FIG. 25, or it can be put inseries with R12 since the diode is a blocking device in terms of thedirection of current flow allowed to the HV pin of the driver. R12serves to limit the inrush current for the capacitor C4 and can alsoexternalize some of the power dissipation in the linear regulator thatdrops the high-voltage (up to 187Vpk) to around 20V for the internaldriver circuits.

In this and some other embodiments, the LEDs are not 3V LEDs, but have aforward voltage Vf of 6V (such as having two die in series in a packageor using an alternative technology such as OLED (Organic LED) for thediodes). To keep voltage to a nominal 24V, the diodes are arranged in a4-in-series group (which has eight diodes), with two groups in parallel.There is a common anode between the two groups. To ensure matchedcurrents in each group, a current mirror is added as T2. In onesimplified embodiment, T2 is a matched pair of NPN transistorsconfigured as a current mirror. The left transistor has base andcollector tied, forming the anode of a diode equivalent, with theemitter being the cathode of the diode. When current flows through thatdiode equivalent, a forward voltage Vf (expressed as Vce or Vcb)develops as a function of that current. Since the transistors arematched pairs, the second transistor's Vbe increases or throttlescurrent until it has a forward voltage Vf more or less matched to theforward voltage Vf of the first transistor. Further variations, withother types of current mirrors, are readily devised or are familiar tothose skilled in the art.

In another variation, eight 3V devices in series are used in either FIG.25 or FIG. 25a (or variation thereof) as the LED arrangement. In furthervariations, more than two groups of LEDs can be arranged in parallel,with each group having another transistor of a current mirror inanalogous arrangement to the two group current mirror of FIG. 25a . Theadditional current mirror transistors are connected similarly to theright transistor in T2, while the left transistor is the currentreference that gets matched. Ideally, all of the transistors arematched. Because of the current mirror, the anode side of the LEDs isone more diode drop removed from neutral (about 0.7V) because of thetransistor that was inserted. In these embodiments, either of thetransistors or any of the diodes, including a LED, or plurality of LEDsopens that fully open the circuit, could create a single faultcondition.

FIG. 26 shows the circuit of FIG. 25 with switch T1 on, illustrating amain current path, and a small current path for the controller circuit.When switch T1 is closed, note that the diode string is tied to Neutralvia D5 and that its total string voltage cannot go above approximately,the string node voltage that is being probed/touched plus the dropacross D5. The assumption is that it is the diode string and itsconnections that are a shock hazard risk due to a single fault in itsinsulation and that the rest of the circuits have a more robustinsulation insulation/housing. If diode D5 fails short, the diodevoltage drop goes to zero; if it or any of the LEDs, or full groupingsof LEDs, in series opens, a single fault shock hazard is presented.Generally speaking, a shock hazard would only be present in the event ofa double fault if possible load touchpoints are insulated and theinsulation also fails. If there is not a second level of protection,such as insulation of touchpoints, a further optional method ofprotection is described as a feature.

FIG. 27 shows the circuit of FIG. 25 with switch T1 off, exhibiting acomparatively low shock hazard risk. When the switch T1 is open, theenergy storage device L2 supplies power to the load, D11-D19 in oneembodiment. A minimalized shock hazard is present, with this currentpath when the switch is open. This current is limited by the currentdrawn by the controller, though, so is not a big concern since thecontrollers typically have about 2 mA or less current through them. Withthe device shown in the figure, a maximum current is specified as 1.2mA.

When the Line is negative with respect to Neutral (or eventually“earth”), current flows from Neutral through steering (or “switching” or“steering”—these terms can be used interchangeably) device D10 (ignoringone embodiment's EMI filter that is placed between these nodes—a noisefilter and its placement are optional to the embodiment) to the positiveside of the load, LEDs D11-D19. A steering/blocking device D9 prevents ashort circuit to the Line. The negative side of the load's current isblocked from Neutral by steering device D5, and is steered by device D8to energy storage device L2, an inductor in one embodiment. Steeringdevices D4 and D6 block a short circuit to the Line. Steering device D9blocks current from going into the load while switching device T1 is onand steers current from the energy storage device L2 into the load whenswitching device T1 is off. Steering device D7 will supply current tothe buck controller throughout this half AC cycle.

The current flow paths for this half of the AC cycle, with switch T1 onand off, respectively, are shown in the following figures. A maincurrent path, a small current path for the controller circuit and for adamper resistor in the EMI filter implementation (the filter is anoptional functional block in the TCA (6)).

FIG. 28 shows the circuit of FIG. 25 with switch T1 on, illustrating amain current path and a small current path. When switch T1 is closed,note that the diode string is tied to Neutral via D10 and that its totalstring voltage cannot go below, approximately, the string node voltagethat is being probed/touched, relative to the anode of D11, plus thedrop across D10. The assumption is that it is the diode string and itsconnections that are a shock hazard risk due to a single fault in itsinsulation and that the rest of the driver circuits have a more robustinsulation insulation/housing. If diode D10 fails short, the diodevoltage drop goes to zero; if it opens, a single fault shock hazard ispresented. Generally speaking, a shock hazard would only be present dueto a double fault if there is an insulation failure on the loadwiring/components touch points. If there is not, a further optionalmethod of protection is described as a feature.

FIG. 29 shows the circuit of FIG. 25 with switch T1 off, illustrating aminimal shock hazard. When the switch T1 is open, the energy storagedevice L2, an inductor in one embodiment, supplies power to the load,D11-D19 in one embodiment. A minimal shock hazard is present with thecurrent path when the switch is open. This current is limited by thecurrent drawn by the controller, though, so is not a big concern sincethe controllers typically have about 2 mA or less current through them.

As previously noted, a single fault shock hazard does present itself ifthe steering devices D10 or D5 devices fail open circuit during thetimes that the switch T1 is closed. One embodiment would be to recognizethat functional steering devices at D5 and D10 will have a very lowvoltage drop across them, for a diode, about 2V or less, for a switch(or transistor), as little as near-zero volts. Sensing a voltage dropacross the D5 and D10 devices could be used to initiate protectionactions such as opening switch T1, using a relay disconnect, oractivating a “crowbar” across line and neutral to open a protectiondevice, such as a fuse, permanently.

The operation of the buck controller, however, relies upon a currentpath between line and neutral, so opening that connection with an openD10 or D5 device will cause the controller to turn off and the switch T1to stay open circuit as a consequence of the controller being turned offand, in an alternative embodiment, aided by a pull-down resistor betweenthe gate and source of the switch MOSET. The circuit is, therefore,inherently double fault protected during the “on” switch cycle. In oneembodiment, however, a “hold-up” capacitor C4 is used to hold Vcc of thecontroller on during short periods of time, possibly multiple AC cycles.The controller, however, can be, and is in one embodiment, implementedwith a low voltage lockout that senses the absence of a voltage acrossLine/Neutral, which then turns off switch T1. The circuit in oneembodiment is, again, inherently fault tolerant. The only other possibleshock hazard is if control circuitry draws more than the few milliampsassumed. Here, an under voltage lockout (UVLO) that turns off switch T1does nothing to mitigate the shock hazard. One embodiment reduces thecurrent draw during UVLO; another embodiment fires a crowbar circuit toopen the fuse on the line side during UVLO.

In another embodiment, Neutral is held as a “virtual” zero voltage levelby the power supply circuit and the Line voltage is always supplied as apositive voltage with respect to neutral. Again, a bridge or otherrectifier is not used. Instead, a conventional buck converter is usedwhen the Line voltage is more positive than the Neutral line connection.This lends itself to a very efficient power supply design for thatpositive half cycle of the AC waveform. In many description instances inthe present disclosure, it is assumed that a lower voltage than line isdesired at the load or that a power factor circuit is not used. Nothingprecludes the addition to, or replacement of, the buck with a boost, orany combination thereof, in any further embodiment described herein.Control functions and the load are all on a positive supply relative toLine/earth. This is shown in the following figure.

FIG. 30 is a block diagram illustrating concepts of operation of thebuck converter in an electronic driver circuit for an embodiment of theLED lamp. Rather than swap Neutral and Line during the negative halfcycle of the AC waveform, as with a bridge rectifier, the Line voltageis boosted above neutral to a positive voltage or current that can thenbe presented directly to the load, or to the buck converter. In oneembodiment, the voltage of the boost circuit is boosted by double theNeutral to peak voltage using an inverting boost circuit. As a result,the load can always be tied directly to Neutral, with the buck converteralways operating from a power input that is always positive with respectto Neutral/earth. At the peak of the AC cycle, as an example of oneembodiment shown in the following figure, the Line connection isactually, and nominally, at −170V for a 120 VAC mains supply. The boostcircuit applies −340V, referred to the Line side, which results in +170Vwith respect to Neutral. By doing so, the load can always be referencedto Neutral and, in the case of a LED string, the voltage anywhere on thestring cannot be any higher with respect to earth than the LED stringvoltage, plus possibly a diode drop if those versed in the art decide touse one to separate sources of current to the load.

One fault that has not been mitigated is a Line/Neutral interchangewiring fault and, in many instances such as hardwired connections madeby licensed experts/craftspeople, is not a concern for mitigation. Withthe presence of an earth connection, this type of fault is easilydetected by those versed in the art, such as, for example, measuringcurrent injected or drawn from Line to earth and Neutral to earth. Inany case, failure of the mitigating means of the present embodiments anda Line/Neutral interchange is a double fault condition.

In devices such as light bulbs, an earth connection is not connected bywire. Here we can implement a “ground fault” protection means, such asthat described in the provisional patent application to which thepresent application claims benefit of priority. In that method, theoutbound current to the LED string is measured, and then compared to theinbound current from the LED string. Any difference in current, apartfrom miniscule leakage currents, would indicated an alternate means ofconduction is bypassing the inbound current—most likely a conductivepath by flora or fauna to earth. At that point a protective means isinitiated, comprising such actions as a crowbar to open the fuse,swapping line and neutral connections, or opening the connection to theLED string. Other means, such as radio frequency (RF) effects could alsobe used to detect line/ground swaps where, in one embodiment, theimpedance of the correct Neutral to earth connection is lower than thecorrect Line to earth impedance, since RF impedance is relative to anearth connection. It should be appreciated that the shock mitigationmechanism may be applied to circuits other than those using LEDsincluding such apparatus as power supplies, motors, other forms oflighting, etc.

Detailed illustrative embodiments are disclosed herein. However,specific functional details disclosed herein are merely representativefor purposes of describing embodiments. Embodiments may, however, beembodied in many alternate forms and should not be construed as limitedto only the embodiments set forth herein. It should be appreciated thatthe embodiments may be extended to other devices besides lamps orlighting devices. For example, the embodiments may be extended to powersupplies, low voltage electric motors, or any other suitable electricapparatus.

It should be understood that although the terms first, second, etc. maybe used herein to describe various steps or calculations, these steps orcalculations should not be limited by these terms. These terms are onlyused to distinguish one step or calculation from another. For example, afirst calculation could be termed a second calculation, and, similarly,a second step could be termed a first step, without departing from thescope of this disclosure. As used herein, the term “and/or” and the “/”symbol includes any and all combinations of one or more of theassociated listed items.

As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”,“comprising”, “includes”, and/or “including”, when used herein, specifythe presence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof. Therefore, the terminology usedherein is for the purpose of describing particular embodiments only andis not intended to be limiting.

It should also be noted that in some alternative implementations, thefunctions/acts noted may occur out of the order noted in the figures.For example, two figures shown in succession may in fact be executedsubstantially concurrently or may sometimes be executed in the reverseorder, depending upon the functionality/acts involved.

Although the method operations were described in a specific order, itshould be understood that other operations may be performed in betweendescribed operations, described operations may be adjusted so that theyoccur at slightly different times or the described operations may bedistributed in a system which allows the occurrence of the processingoperations at various intervals associated with the processing.

Various units, circuits, or other components may be described or claimedas “configured to” perform a task or tasks. In such contexts, the phrase“configured to” is used to connote structure by indicating that theunits/circuits/components include structure (e.g., circuitry) thatperforms the task or tasks during operation. As such, theunit/circuit/component can be said to be configured to perform the taskeven when the specified unit/circuit/component is not currentlyoperational (e.g., is not on). The units/circuits/components used withthe “configured to” language include hardware—for example, circuits,memory storing program instructions executable to implement theoperation, etc. Reciting that a unit/circuit/component is “configuredto” perform one or more tasks is expressly intended not to invoke 35U.S.C. 112, sixth paragraph, for that unit/circuit/component.Additionally, “configured to” can include generic structure (e.g.,generic circuitry) that is manipulated by software and/or firmware(e.g., an FPGA or a general-purpose processor executing software) tooperate in manner that is capable of performing the task(s) at issue.“Configured to” may also include adapting a manufacturing process (e.g.,a semiconductor fabrication facility) to fabricate devices (e.g.,integrated circuits) that are adapted to implement or perform one ormore tasks.

The foregoing description, for the purpose of explanation, has beendescribed with reference to specific embodiments. However, theillustrative discussions above are not intended to be exhaustive or tolimit the invention to the precise forms disclosed. Many modificationsand variations are possible in view of the above teachings. Theembodiments were chosen and described in order to best explain theprinciples of the embodiments and its practical applications, to therebyenable others skilled in the art to best utilize the embodiments andvarious modifications as may be suited to the particular usecontemplated. Accordingly, the present embodiments are to be consideredas illustrative and not restrictive, and the invention is not to belimited to the details given herein, but may be modified within thescope and equivalents of the appended claims.

What is claimed is:
 1. A lamp, comprising: at least one light emittingdiode (LED); an electronic circuit configured to provide power to the atleast one LED at least one flat circuit board having mounted thereto theat least one LED and the electronic circuit; and within the at least oneflat circuit board is disposed a heatsink to dissipate heat from the atleast one LED and a plurality of circuit paths for the electroniccircuit within the at least one flat circuit board.
 2. The lamp of claim1, wherein the at least one LED comprises a first LED mounted to a firstface of the at least one flat circuit board, and a second LED mounted toa second face of the at least one flat circuit board.
 3. The lamp ofclaim 1, wherein the at least one LED comprises at least two LEDs inseries electrical connection, mounted to a light center of a first faceof the at least one flat circuit board.
 4. The lamp of claim 1, furthercomprising: a lens mounted to the at least one LED and configured tocorrect a light pattern of the at least one LED to a full hemisphere. 5.The lamp of claim 1, wherein the at least one flat circuit boardincludes one of a substrate that is an electrical insulator and athermal insulator, and a layer with electrical conductivity and thermalconductivity or a substrate that is an electrical insulator and athermal conductor, and a layer with electrical conductivity and thermalconductivity.
 6. The lamp of claim 1, wherein the electronic circuitcomprises: a buck converter; further circuitry configured to detectcurrent during a first half of an alternating current (AC) cycle anddetect current during a second half of the AC cycle; and the furthercircuitry configured to turn off power provided by the buck converter tothe at least one LED based upon detecting a difference in the currentbetween the first half and the second half of the AC cycle.
 7. The lampof claim 1, wherein: the at least one flat circuit board includes anelectrically conductive layer, with which the at least one LED and theelectronic circuit are in electrical and thermal contact; and wherein atleast a portion of the electrically conductive layer forms at least aportion of the heatsink.
 8. A lamp, comprising: at least one printedcircuit board that has circuit traces and also functions as a heatsink;at least one light emitting diode (LED) mounted to a thermallyconductive area of the at least one printed circuit board, wherein thethermally conductive area comprises at least a portion of an overallarea of the at least one printed circuit board; and a driver circuitcoupled to the at least one printed circuit board and coupled by the atleast one printed circuit board to the at least one LED, wherein thedriver circuit is configured to detect current to or from a hot orneutral mains connection or through the at least one LED.
 9. The lamp ofclaim 8, further comprising: a portion of the at least one printedcircuit board having a profile dimensioned for rotational insertion intoa threaded socket.
 10. The lamp of claim 8, further comprising: one of alight diffusion device optically coupled to the at least one LED or aremote phosphor device optically coupled to the at least one LED. 11.The lamp of claim 8, wherein the thermally conductive area includes asame material as circuit traces of the at least one printed circuitboard and is configured to conduct heat away from the at least one LEDand dissipate the heat by one of convection, conduction or radiation.12. The lamp of claim 8, wherein: the at least one LED comprises aseries string of LEDs; and one end of the series string of LEDs isconnected to a neutral of the alternating current.
 13. The lamp of claim8, wherein the driver circuit is configured to shut off power to the atleast one LED responsive to the detected current failing to meet apredetermined condition.
 14. A lamp, comprising: at least one flat,printed circuit board; a first light emitting diode (LED) mounted to afirst face of the at least one flat, printed circuit board; a second LEDmounted to an opposed second face of the at least one flat, printedcircuit board; an electronic circuit coupled to the at least one flat,printed circuit board and configured to provide power to the first LEDand the second LED; the at least one flat, printed circuit board havingcircuit paths that couple the electronic circuit, the first LED and thesecond LED; and the at least one flat, printed circuit board configuredto act as a heatsink to dissipate at least one half watt of heat from atleast the first LED or the second LED, wherein the at least one flat,printed circuit board and a further flat, printed circuit board havingcomplementary mating features dimensioned so that the at least one flat,printed circuit board and the further flat, printed circuit board areassembled to each other with the mating features engaged.
 15. The lampof claim 14, further comprising: a parabolic reflector, arranged withthe at least one flat, printed circuit board so that the first LED andthe second LED are located at a light center of the parabolic reflector.16. The lamp of claim 14, further comprising: the electronic circuitincluding a communication port with a connector included in or mountedto the at least one flat, printed circuit board.
 17. The lamp of claim14, wherein: the at least one flat, printed circuit board comprises athermally conductive area that includes an electrically conductivelayer, to act as the heatsink; the circuit paths include theelectrically conductive layer; and the electrically conductive layer ofthe thermally conductive area has thermal performance enhanced ascompared to the electrically conductive layer of the circuit paths. 18.The lamp of claim 14, further comprising: the at least one flat, printedcircuit board having a thermally conductive area, as the heatsink, inthermal contact with the first LED and the second LED; and the thermallyconductive area acts as an integrated reflector, or filter, for light ofthe first LED or the second LED.
 19. The lamp of claim 14, wherein allelectrical connections coupling the electronic circuit, the first LEDand the second LED are formed in the electronic circuit and on the atleast one flat, printed circuit board, without external wires.